249 



opening by which its entrance was effected, had moved along 

 the sash, and by repeated tappings had broken numerous 

 holes, till one was made sufficiently large for its passage out ; 

 f(5r there were two holes found of sufficient size, one broken 

 from within and one from without. 



Baron Osten Sacken, Russian Consul at New York, and 

 Dr, John J. Craven, U. S. A., were elected Corresponding 

 Members. 



Messrs. John Quincy Thaxter and Charles Bartlett, of 

 Boston, and Dr. John E. Tyler, of Somerville, were elected 

 Resident Members. 



JTune 17, 1863. 

 The President in the chair. 

 The following paper was presented : — 

 Malacozoological Notices, No. 1. By Dr. William Stimp- 



SON. 



In some recent investigations among the MoUusca of the District of 

 Columbia, a few facts have been observed which may be worthy of 

 being placed on record.* 



I, On the Genus Gundlachia. 



This name was proposed by Dr. Pfeiffer (Zeitschrift fiir Malak. 

 1849, p. 97, and 1853, p. 180) for a remarkable shell discovered by 

 Dr. Gundlach in the fresh-water lakes of Cuba. The specimens first 

 described were not adult, and had the appearance of an Ancylus with 

 the posterior two-thirds of its aperture closed by a horizontal septum, 

 and it was not until several years afterwards that the adult was discov- 

 ered, when it was found that the shell first described was merely the 

 apicial portion of a much larger and somewhat crepiduliform shell, 

 the form figured by H. & A. Adams, in their " Genera of Recent 

 Mollusca," plate lxxxiv., fig. 8. From the tenuity, and other general 

 characters of the shell, as well as the want of an operculum, the ge- 

 nus was rightly presumed to belong near the Limnacid«, and to be 

 nearly allied to Ancylus, 



* For the cuts which form the illustrations of these "Notices," I am indebted 

 to the liberality of the Smithsonian Institution. 



